Adaptive Patient Interface

ABSTRACT

A patient interface for an ophthalmic system can include an attachment module, attachable to the ophthalmic system, and a contact module, configured to accommodate a viscoelastic substance between the patient interface and a procedure eye. The viscoelastic substance can include a fluid, a liquid, a gel, a cream, an artificial tear, a film, an elastic material, or a viscous material. The refractive index of the viscoelastic substance can be within a range of approximately 1.24-1.52 at an operating wavelength of the ophthalmic system. The patient interface can further include input ports, output ports, and a suction system. It can be an integrated design or a multi-piece patient interface. The viscoelastic substance can be provided by injection, on the cornea, at the contact module, or in a space bounded by soft elastic films or membranes, such as in a bag.

BACKGROUND

1. Field of Invention

This patent document relates to patient interfaces that attach anophthalmic system to an eye for anterior segment eye procedures. Moreparticularly, this patent document relates to adaptive patientinterfaces that reduce a deformation of a cornea of the procedure eye.

2. Description of Related Art

This patent document describes examples and embodiments of techniquesand devices for securing an ophthalmic system to an eye to perform ananterior segment eye procedure. These devices are often referred to aspatient interfaces. Since patient interfaces serve to connect theophthalmic system and the eye of the patient, their performance is animportant contribution to the precision and success of the ophthalmicprocedures. Thus, improvements in patient interfaces can lead toimprovements in the precision and reliability of ophthalmic procedures.

SUMMARY

Briefly and generally, a patient interface for an ophthalmic system caninclude an attachment module, attachable to the ophthalmic system; and acontact module, configured to accommodate a viscoelastic substancebetween the patient interface and a procedure eye.

In some implementations, the viscoelastic substance can include a fluid,a liquid, a gel, a cream, an artificial tear, a film, an elasticmaterial, or a viscous material.

In some implementations, a refractive index of the viscoelasticsubstance is closer to a refractive index of a cornea of the procedureeye than to a refractive index of air at an operating wavelength of theophthalmic system.

In some implementations, a refractive index of the viscoelasticsubstance is within a range of approximately 1.24-1.52 at an operatingwavelength of the ophthalmic system.

In some implementations, a refractive index of the viscoelasticsubstance is within a range of approximately 1.35-1.41 at an operatingwavelength of the ophthalmic system.

In some implementations, the attachment module and the contact moduleare separate and connectable.

In some implementations, the attachment module and the contact moduleare integrated components of the patient interface.

In some implementations, a component of the patient interface is atleast one of disposable, sterilizable, and reusable.

Some implementations can include one or more input ports to introducethe viscoelastic substance into an accommodation space at leastpartially defined by the contact module.

Some implementations can include one or more output openings configuredto enable a discharge of air, gas, or the viscoelastic substance fromthe contact module.

In some implementations, the one or more output openings can include avent port, configured to keep a pressure in an accommodation space atleast partially defined by the contact module at approximately ambientpressure.

Some implementations can include a suction subsystem configured to atleast partially immobilize the procedure eye for an ophthalmicprocedure.

In some implementations, the suction subsystem is arranged in relationto the contact module; and the suction subsystem is connectable to avacuum suction system to create a partial vacuum between the suctionsubsystem and the procedure eye.

In some implementations, the patient interface is configured to keep achange of an apical curvature of a cornea of the procedure eye below 10%upon an attachment of the patient interface to the procedure eye.

In some implementations, the patient interface is configured to keep achange of the apical curvature of the cornea of the procedure eye below3% upon the attachment of the patient interface to the procedure eye.

In some implementations, the ophthalmic system can include at least oneof an imaging system, a diagnostic system, a laser system, and anophthalmic surgical system.

In some implementations, the contact module is configured to accommodatethe viscoelastic substance before being attached to the procedure eye.

In some implementations, the contact module is configured to accommodatethe viscoelastic substance after the viscoelastic substance has beenapplied to the procedure eye.

In some implementations, the contact module can include a soft elasticfilm or membrane, configured to contain the viscoelastic substance in anaccommodation space at least partially defined by the contact module,and to form a soft and elastic contact surface for the procedure eye.

Some implementations can include a soft bag, containing the viscoelasticsubstance.

In some implementations, the patient interface can be connectable to adegassing subsystem, configured to degas the viscoelastic substance.

In some implementations, a patient interface for an ophthalmic systemcan include a contact module, configured to be attachable to a first eyewith an apical corneal radius of R1 and separately to a second eye withan apical corneal radius of R2; and to limit a change of each apicalcorneal radius to less than 0.5*|R1-R2| when the contact module isattached to the first eye and separately to the second eye, wherein theapical corneal radii R1 and R2 are between 7.5 mm and 8.2 mm.

In some implementations, the contact module can be configured to limitthe change of each apical corneal radius to less than 0.25*|R1-R2| whenthe contact module is attached to the eyes.

Some implementations can include an attachment module attachable to theophthalmic system, wherein the attachment module and the contact modulecan be either separate and connectable, or integrated components of thepatient interface.

Some implementations can include one or more fluid ports, configured tointroduce a fluid or gel into a containment space at least partiallydefined by the procedure eye and the patient interface.

Some implementations can include one or more output ports, configured toenable a discharge of at least one of air, fluid or gel from acontainment space at least partially defined by the patient interfaceand the procedure eye.

Some implementations can include a suction port, configured to enable acreation of a partial vacuum between a portion of the patient interfaceand a portion of the procedure eye.

Some implementations can include a distal lens, wherein the distal lensdoes not contact a cornea of the procedure eye after an attachment ofthe patient interface to the procedure eye.

Some implementations can include a soft layer, configured to contain aviscoelastic substance, and to provide a soft contact surface for aprocedure eye.

In some implementations, a method of utilizing a patient interface foran ophthalmic procedure can include applying the patient interface to aprocedure eye in preparation for the ophthalmic procedure; and providinga viscoelastic substance to at least one of a cornea of the procedureeye and a contact portion of the patient interface, wherein theproviding is performed before, during or after the applying.

In some implementations, providing the viscoelastic substance caninclude providing a fluid, a liquid, a gel, a cream, an artificial tear,a film, an elastic material, or a viscous material.

In some implementations the providing can include introducing theviscoelastic substance through an input port of the patient interfaceinto a contact space, at least partially bordered by the patientinterface and the procedure eye after the applying.

In some implementations the providing can include introducing theviscoelastic substance onto the cornea of the procedure eye before theapplying.

In some implementations the providing can include providing theviscoelastic substance at the contact portion of the patient interfacebefore the applying.

In some implementations the providing can include providing theviscoelastic substance in a space at least partially defined by one ormore soft films or membranes.

In some implementations the providing can include using a syringe tointroduce the viscoelastic substance.

In some implementations the ophthalmic procedure can include at leastone of an imaging procedure, a diagnostic procedure, a laser-assistedprocedure, and an ophthalmic surgical procedure.

Some implementations can include degassing the viscoelastic substance.

In some implementations the degassing can include at least one ofreducing a pressure, heating, performing membrane degasification,substituting an inert gas, and adding a reductant.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A illustrates an integrated patient interface 100.

FIG. 1B illustrates the patient interface 100 attached to the ophthalmicsystem 10 and the procedure eye 20.

FIG. 2A-B illustrate a two-piece patient interface 100′.

FIG. 3 illustrates another embodiment of a two-piece patient interface100″.

FIG. 4 illustrates a method of utilizing a patient interface.

FIGS. 5A-B illustrate different sequences of the method of FIG. 4.

FIGS. 6A-H illustrate various implementations of providing aviscoelastic substance for the ophthalmic procedure.

DETAILED DESCRIPTION

Some laser eye surgical procedures, such as corneal refractivecorrections and laser-assisted lens capsulotomies, may benefit fromimmobilizing the procedure eye relative to the surgical laser systemduring the procedure. Some systems include a so-called patient interfaceto carry out this task. One end of the patient interface can be attachedto the distal end of the surgical laser system. The other end caninclude a contact lens pressed against the procedure eye. Such patientinterfaces hold the eye steady relative to the surgical laser, enablinga high precision directing and focusing of the laser beam to apredetermined target location of the eye. Some patient interfaces canalso be used to provide a reference surface for the targeting of thelaser so that its focus depth can be defined relative to the contactlens.

Some patient interfaces use flat contact “lenses”, also calledapplanation plates. Others include curved contact lenses. In operation,either of these contact lenses can be pressed against the cornea of theeye, essentially immobilizing the eye and forcing the cornea to conformto the contact surface of the contact lens. To overcome the slipperinessof the tear film covering the eye, the contact lenses are typically heldin place by a vacuum system, such as a suction ring.

While using rigid contact lenses has the benefit of providing awell-defined optical element for optimizing the beam properties of thelaser, and possibly of providing a reference plane to direct thesurgical laser with precision, there are also disadvantages associatedwith forcing rigid lenses against the procedure eye.

One of the problems is that upon docking to the eye, the contact lenstypically deforms the cornea, as their curvatures are generallydifferent from each other. This change of the corneal curvature cancause internal deformations since the support system of the lens of theeye is very soft. Therefore, the docking of a rigid patient interfacetypically shifts and tilts the lens relative to the optical axis of theeye. This displacement and tilt may make the cuts of a typical cataractsurgery, the circular capsulotomy cut on the capsular bag and thecataract surgical pattern cut in the lens itself, off-center anddistorted, leading to a deterioration of the optical outcome of thecataract procedure.

Altering the cornea's natural curvature may also produce wrinkles on thesurface of the cornea that could distort the laser beam. This distortioncan lead to increased scattering and astigmatism of the beam, possiblyrequiring the use of a higher energy laser beam. The distortion can alsolead to a loss of precision of the directing the laser beam.

The corneal deformation can be reduced by designing the contact lens tohave a curvature equaling that of a typical cornea. However, sincecorneal radii vary considerably from patient to patient, even thesepatient interfaces deform the corneas of most patients.

To address these problems, some implementations of the present inventionmay use a patient interface whose lens does not make direct contact withthe cornea. Such an embodiment can successfully minimize the cornealdeformation, reducing the aforementioned problems, possibly evenavoiding them altogether.

However, such non-contact designs may have their own challenges as (1)the light propagating through an air gap before entering the cornea mayreduce the beam quality by increasing its astigmatism, for example; (2)the surface of the cornea can dry out quickly, increasing the lightscattering at the corneal surface considerably; and (3) the surgical eyemay have an excessive amount of movement because the patient interfacedoes not hold it steady by direct contact.

Implementations of the present invention include patient interfaces thatreduce the corneal deformation because their lenses do not make directcontact with the cornea, while at the same time offer solutions for theabove three challenges.

FIG. 1A illustrates an implementation of a patient interface, or PI,100. The PI 100 can include an attachment module 110 and a contactmodule 120. A function of the attachment module 100 can be to attach thePI 100 to an ophthalmic system 10. In some embodiments the attachmentmodule 110 can be connected to a distal end, application tip, orobjective of the ophthalmic system 10. A function of the contact module120 can be to form a connection to an eye 20 on which an ophthalmicprocedure is performed. This eye will be sometimes referred to as theprocedure eye 20.

The ophthalmic system 10 can include an imaging system, a diagnosticsystem, a laser system or an ophthalmic surgical system.

The PI 100 can include a distal lens, or non-contact lens 111. Thedistal lens 111 can be the last refractive element of the optical trainof the ophthalmic system 10. The distal lens 111 can be a flatapplanation plate or a lens with one or both surfaces curved. Its rolecan be similar to that of the contact lens of other patient interfaces,with the difference that in various embodiments the distal lens 111 doesnot contact a cornea 21 of the eye 20. For this reason, the distal lens111 does not deform the cornea 21, thus avoiding the displacement andtilt of lens 22, and the wrinkling of the cornea 21.

FIG. 1B illustrates the PI 100 after it has been connected or docked tothe eye 20. Visibly, in this implementation the distal lens ornon-contact lens 111 is indeed not in direct contact with the cornea 21of the eye 20. Because of this lack of contact, the PI 100 minimizes thedeformation of the eye.

A measure of the deformation is the relative change of an apicalcurvature of the cornea of the procedure eye when the patient interfaceis attached to the procedure eye. Some embodiments of the PI 100 keepthe change of the apical curvature of the cornea below 10% when the PIis attached to the eye. In other embodiments, the relative change of theapical corneal curvature can be kept below 3%.

Referring to FIG. 1A, the contact module 120 can be formed toaccommodate a viscoelastic substance 121 in a space between the PI 100and the cornea 21. This design can address the above challenge (1),since when the viscoelastic substance 121 fills up the space between thedistal lens 111 and the cornea 21, the laser beam or light of theophthalmic system 10 does not propagate through air.

When there is an air gap between the distal lens 111 and the cornea ofthe procedure eye 20, the surgical or diagnostic light beams arerefracted at the posterior surface of the distal lens 111 and at theanterior corneal surface. This latter refraction is proportional to(n(a)−n(c)), the difference between the refractive index n(a) of theair, and n(c), that of the cornea.

The deterioration of the beam quality can be reduced by filling up theair gap with the viscoelastic substance 121 between the patientinterface 100 and the cornea 21. In this case, the beam refraction andastigmatism will be proportional to (n(v)−n(c)), where n(v) is an indexof refraction of the viscoelastic substance 121.

Thus, in some embodiments the viscoelastic substance 121 can be chosento have a refractive index n(v) closer to n(c), the refractive index ofthe cornea, than to n(a), the refractive index of air, at an operatingwavelength of the ophthalmic system 10. Since an index of refraction ofthe cornea is typically close to n(c)=1.38, in some embodiments thistranslates to the viscoelastic substance 121 having an index ofrefraction n(v) in the approximate range of 1.24-1.52. In otherembodiments, n(v) can fall in the approximate range of 1.35-1.41.

Introducing the viscoelastic substance 121 to fill the space between thedistal lens 111 of the patient interface and the cornea 21 also resolveschallenge (2) as the cornea is not exposed to air in this design.Rather, the corneal surface can remain wetted by the viscoelasticsubstance 121, preventing the cornea 21 from drying out.

In various implementations, the viscoelastic substance 121 can be one ofa wide variety of substances, including a fluid, a liquid, a gel, acream, an artificial tear, a film, an elastic material, or a viscousmaterial. In some cases, two or more of these substances can be presentin the viscoelastic substance 121.

The viscoelastic substance 121 can be inserted through an input port 122into an accommodation space 123. The accommodation space 123 can havenumerous different embodiments: it can be a concave space at leastpartially defined by the contact module 120 and the distal lens 111, orit can be any recessed chamber of the patient interface 100. It can bealso defined by a combination of the contact module 120, the distal lens111 and the accommodation module 110.

FIG. 1B illustrates that phase of the operation of the PI 100 when thePI 100 has been docked to the eye and the viscoelastic substance hasbeen introduced into the accommodation space 123 through the input port122, essentially filling up the space or air gap between the distal lensand the cornea.

Implementations of the PI 100 can include an output opening or vent port124. The vent port 124 can have several functions, including dischargingthe air, displaced by the viscoelastic substance 121, from theaccommodation space 123. Also, the viscoelastic substance 121 itself canbe discharged from the accommodation space 123 through this vent port124, thus accelerating its introduction into the accommodation space123. Doing so also increases the homogeneity of the spatial distributionof the viscoelastic substance 121.

Further, the vent port 124 can be configured to keep a pressure in theaccommodation space 123 close to the ambient pressure. Thisfunctionality can reduce or prevent unintended gas seepage across thecontact module 120. The vent port 124 can be also used to degas theintroduced viscoelastic substance 121, as described below in moredetail.

In various embodiments, there can be more than one input ports 122 andmore than one output openings 124.

A vacuum suction system 130 can be attached to a suction subsystem 132through a suction port 133 in some embodiments. The suction subsystem132 can be configured to at least partially immobilize the procedure eye20 for an ophthalmic procedure. An example of the suction subsystem 132is a suction ring formed as part of the contact module 120. The suctionring 132 can include a skirt or vacuum seal formed to make an airtightcontact with the eye. Applying suction through the suction port 133 cankeep the eye steady.

Several different types of the suction subsystem 132 are known. Theaforementioned suction ring is one of them, where the partial vacuumacts on a ring around the cornea. In other implementations the partialvacuum can be applied to larger portions of the accommodation space 123.More than one suction chamber can also be formed.

In the implementation of FIG. 1A-B, the attachment module 110 and thecontact module 120 are components of a one-piece, integrated patientinterface 100. An aspect of this integrated PI 100 is that sometimes theprecise aligning and docking of the PI 100 to the procedure eye 20 canbe time consuming, as it can require the adjustment of a portion of theophthalmic system 10. This movement can involve moving a gantry or anarticulated arm of the ophthalmic system 10 that contains lenses andmirrors. Therefore, this movement can require more complex technicalsolutions.

FIG. 2A illustrates another embodiment of a patient interface 100′ thatimproves the efficiency of the docking of the PI 100′ and simplifies itstechnology. The PI 100′ achieves these features by having a separateattachment module 110′ and a separate contact module 120′.

The attachment module 110′ can be attached to the distal end of theophthalmic system 10 or 10′, such as to its objective, with ease, asthis step does not require aligning the ophthalmic system with the eye.The separate contact module 120′ can include a so-called gripper (notshown). A variety of the presently known grippers can be combined withthe contact module 120′ to provide improved control and ease ofmanipulations for the operator of the system. The contact module 120′ isalso relatively easy to dock to the eye as moving and adjusting it doesnot require moving an articulated arm of the ophthalmic system 10′.

FIG. 2B illustrates that once the attachment module 110′ is attached tothe ophthalmic system 10′ and the contact module 120′ is docked to theeye, an operator of the system, such as a surgeon, can gently move thegripper to align the contact module 120′ with the attachment module110′. When an alignment is achieved in the x-y directions, theattachment module 110′ can be gently lowered onto the contact module120′ to complete a connection at a contact rim 126′, completing thepatient interface 100′. Once a sufficient seal has been established, aviscoelastic substance 121′ can be provided through an input port 122′into an accommodation space 123′, at least partially defined by the PI100′ and the cornea 21.

Most of the elements of the PI 100′ are analogous to the correspondingelements of PI 100 and are labeled accordingly. Thus, their earlierdescription is not repeated here.

In the embodiment of FIGS. 2A-B of the PI 100′, a distal lens 111′ canbe part of the attachment module 110′.

FIG. 3 illustrates another two-piece implementation PI 100″, where adistal lens 111″ is either part of a contact module 120″ or can beinserted into the contact module 120″. This PI 100″ can be completed byagain docking the contact module 120″ to the eye, attaching anattachment module 110″ to an ophthalmic system 10″, aligning the two andgently lowering the attachment module 110″ onto the contact module 120″so that a receiving rim 113″ of the attachment module 110″ makes contactwith a contact rim 126″ of the contact module 120″. After the contactwas completed and a sufficient seal has been established, a viscoelasticsubstance 121″ can be provided e.g. through an input port 122″.

While the embodiments of FIG. 2 and FIG. 3 were referred to as two-piecePIs, the scope of the embodiments is broader and includes allmulti-piece PIs that have two or more components or modules. Thesemultiple components can be connectable to form an attachment module, acontact module, or additional modules with additional functionalities.

Of course, as in all medical processes, providing and securing a sterileenvironment for the patient is of paramount importance. This requirementcan be satisfied by some embodiments of the patient interface 100, orone of its components, being disposable. In other embodiments, where thepatient interface 100 or one of its components is reusable, this can beachieved e.g. by the PI 100 being sterilizable.

One reason why implementations of the patient interface 100 can keep thedeformation of the cornea lower than previous systems is that they areadaptive. The surface that contacts the eye is not a rigid, or hardlens, but a deformable, soft surface. Thus, after docking the contactmodule 120 to the eye and introducing the viscoelastic substance 121,the radius of the contact surface, formed by the viscoelastic substance,can adapt to the radius of the cornea.

As pointed out above, even rigid contact lenses can limit thedeformation of a particular cornea to a minimal degree, or even to zero.However, the corneal radius of curvature varies from patient to patient.Thus, rigid-lens systems cannot minimize the corneal deformation for agroup of patients.

In contrast, the above-described patient interfaces with adaptive, ordeformable, contact surfaces can minimize the corneal deformation of agroup of patients with varying corneal radii. One way to capture thisfact is that if the contact module 120 of the PI 100 is attached to afirst eye with an apical corneal radius of R1 and causes a δR1 change ofthis corneal radius, and separately, it is attached to a second eye withan apical corneal radius of R2, and causes a 6R2 change of that cornealradius, then the contact module 120 is capable of limiting 6R1 and 8R2to be less than 0.5*|R1-R2|, the lowest value a rigid contact lens couldachieve as a joint limit for both radius changes. Implementations of theadaptive PIs can satisfy this condition in relation apical corneal radiiR1 and R2 in the range typical for human eyes, between 7.5 mm and 8.2mm. In some other implementations, the PI 100 can limit 6R1 and 6R2 tobe less than 0.25*|R1-R2|.

FIG. 4 illustrates a method 200 of utilizing the patient interface 100for an ophthalmic procedure. The method 200 can include the following:

210—applying the patient interface to a procedure eye in preparation forthe ophthalmic procedure; and

220—providing a viscoelastic substance to at least one of a cornea ofthe procedure eye and an accommodation portion of the patient interface,wherein

the providing is performed before, during or after the applying.

The step 210 can include aligning a one-piece patient interface 100 withan optical axis of the eye, followed by lowering and docking the patientinterface 100 to the eye. After docking, the eye can be held steady byapplying at least a partial vacuum to a suction subsystem of the patientinterface 100. As mentioned before, two-piece patient interfaces 100′and 100″ can be applied to the eye by attaching the attachment module110′/110″ to the distal end of the ophthalmic system 10′/10″, dockingthe contact module 120′/120″ to the eye, aligning the attachment module110′/110″ and the contact module 120′/120″, and finally lowering theattachment module 110′/110″ to dock it to the contact module 120′/120″.Again, the application of a partial vacuum can be used to hold the eyesteady.

For either one-piece or two-piece interfaces, the providing step 220 caninclude introducing the viscoelastic substance 121/121′/121″ into theaccommodation space 123/123′/123″. As before, the viscoelastic substance121/121′/121″ can include a fluid, a liquid, a gel, a cream, anartificial tear, a film, an elastic material, or a viscous material.

In the method 200, the ophthalmic procedure can be an imaging procedure,a diagnostic procedure, a laser-assisted procedure, or an ophthalmicsurgical procedure.

FIG. 5A illustrates that a providing step 220′ can be performed after anapplying step 210′.

FIG. 5B illustrates that a providing step 220″ can be performed beforean applying step 210″. In some cases, the providing step 220 and theapplying step 210 can be performed in a partially overlapping manner.

FIGS. 6A-G illustrate that in various implementations the viscoelasticsubstance can be provided in several different manners. Elementsanalogous to the elements in earlier embodiments will not be expresslydescribed and at some places will even be omitted for clarity.Nevertheless, combinations with the analogous elements from FIGS. 1-5are all within the scope of the invention.

FIGS. 6A-E illustrate various step-sequences for one-piece integratedpatient interfaces.

FIG. 6A illustrates that the providing step 220 can include providingthe viscoelastic substance 121 through the input port 122 of the patientinterface into the contact space 123, where the contact space 123 is atleast partially bordered by the patient interface and the procedure eye,after the applying step 210. Here and in subsequent implementations, theviscoelastic substance 121 can be provided e.g. by using a syringe, orany other suitable applicator.

FIG. 6B illustrates that in some implementations of the providing step220, the viscoelastic substance 121 can be provided onto the cornea ofthe procedure eye before the patient interface is docked to the cornea.Again, a wide variety of applicators can be used, including syringes.

FIG. 6C illustrates that in some implementations of the providing step220, the viscoelastic substance 121 can be provided at the contactmodule or portion 120 of the patient interface before the applying step210. The viscoelastic substance 121 can be introduced, for example, by awide variety of applicators, including syringes. In other cases, theviscoelastic substance 121 can be disposed in the patient interface 100by its manufacturer, affixed to the PI 100 with e.g. a cover sheet orfoil that can be removed by the surgeon to expose and provide the gel orcream of the viscoelastic substance 121.

The injection of certain viscoelastic substances 121, e.g. with asyringe, may lead to the formation of a large number of microscopicbubbles in the injected gel or fluid. Many of these microscopic bubblescan have diameters comparable to the operational wavelength of the laseror light beam, and thus can scatter the beam intensely. For this reason,the bubbles can lead to a pronounced deterioration of the opticalperformance of the system.

FIG. 6D illustrates that in some embodiments the formation of bubblescan be preempted by providing the viscoelastic substance 121 containedwith or within a soft elastic film or membrane 150. In a preparatorystep, the fluid or gel inside the soft elastic film 150 can be carefullyde-gassed and then the film 150 sealed airtight to prevent the formationof bubbles. When the patient interface is docked on the cornea, the softelastic film 150 is not removed, thus preventing the formation of themicroscopic bubbles. Since the membrane 150 is soft and elastic, itstill allows the extensive adaptation of the viscoelastic substance 121to conform to the curvature of the cornea and thus minimize itsdeformation.

Additionally, bubbles may be generated at the contact surface where theviscoelastic substance 121 meets the cornea. Some embodiments managethese bubbles by providing the viscoelastic substance 121 with itsmaximum height, or apex, close to the optical axis of the ophthalmicsystem 10. With this design, when the PI 100 makes first contact withthe viscoelastic substance 121, this contact happens at the center oroptical axis. The continued lowering of the PI 100 extends the contactarea moving radially outward from the center. Even if gas bubbles weretrapped at the contact surface initially, this design presses andsqueezes the bubbles radially outward, largely eliminating them from thepath of the laser beam. This is to be contrasted with designs in whichthe viscoelastic substance 121 does not have the maximal height at thecenter. In these designs gas bubbles may remain trapped at the contactsurface, leading to enhanced light scattering.

FIG. 6E illustrates an embodiment where the viscoelastic substance isprovided at the contact portion 120 of an integrated one-piece patientinterface 100, contained in a space defined by an anterior soft elasticfilm 150 a on an anterior side and a posterior soft elastic film 150 pon the posterior side of the viscoelastic substance 121.

This design can utilize two separate films or a single membranecompletely surrounding the viscoelastic substance 121, in effect formingan elastic containment bag. Such implementations can provide additionalcontrol over the shape of the viscoelastic substance 121.

FIG. 6F illustrates a two-piece patient interface 100′, where theviscoelastic substance 121′ is contained between the two films 150 a and150 p, or inside an elastic bag with two surfaces, at the contact module120′ before it is connected to the attachment module 110′. In thisembodiment, the distal lens is part of the attachment module 110′.

FIG. 6G illustrates a variant implementation of a two-piece patientinterface 100″, where the viscoelastic substance 121″ is again providedin an elastic containment bag or between two soft films 150 a″ and 150p″. In this implementation a distal lens 111″ is part of the contactmodule 120″.

FIG. 6H illustrates yet another variant implementation, where theviscoelastic substance 121″ can be provided and contained in a space atleast partially defined by a soft elastic film 150″ and the distal lens111″.

Some implementations can have additional modules to manage the gas orbubbles, contained either in the viscoelastic substance 121 after itsinjection into the accommodation space 123, or trapped at the contactsurface with the patient interface 100. These additional modules caninclude a degassing subsystem, connectable to the patient interface andconfigured to degas the viscoelastic substance 121 or the contactsurface. Several such degassing systems and methods are known, amongthem: reducing a pressure experienced by the viscoelastic substance 121,heating the viscoelastic substance 121, performing a membrane-baseddegasification, substituting an inert gas for the air atmosphere,manipulating a surface tension of the viscoelastic substance 121, andadding a reductant to it.

While this document contains many specifics, these should not beconstrued as limitations on the scope of the invention or of what may beclaimed, but rather as descriptions of features specific to particularembodiments of the invention. Certain features that are described inthis document in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable subcombination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a subcombination or a variation of a subcombination. Also,variations and enhancements of the described implementations, and otherimplementations can be made based on what is described.

1. A patient interface for an ophthalmic system, comprising: anattachment module, attachable to the ophthalmic system; and a contactmodule, configured to accommodate a viscoelastic substance between thepatient interface and a procedure eye.
 2. The patient interface of claim1, the viscoelastic substance comprising at least one of: a fluid, aliquid, a gel, a cream, an artificial tear, a film, an elastic material,or a viscous material.
 3. The patient interface of claim 1, wherein: arefractive index of the viscoelastic substance is closer to a refractiveindex of a cornea of the procedure eye than to a refractive index of airat an operating wavelength of the ophthalmic system.
 4. The patientinterface of claim 1, wherein: a refractive index of the viscoelasticsubstance is within a range of approximately 1.24-1.52 at an operatingwavelength of the ophthalmic system.
 5. The patient interface of claim1, wherein: a refractive index of the viscoelastic substance is within arange of approximately 1.35-1.41 at an operating wavelength of theophthalmic system.
 6. The patient interface of claim 1, wherein: theattachment module and the contact module are separate and connectable.7. The patient interface of claim 1, wherein: the attachment module andthe contact module are integrated components of the patient interface.8. The patient interface of claim 1, wherein: a component of the patientinterface is at least one of disposable, sterilizable, and reusable. 9.The patient interface of claim 1, comprising: one or more input ports tointroduce the viscoelastic substance into an accommodation space atleast partially defined by the contact module.
 10. The patient interfaceof claim 1, comprising: one or more output openings configured to enablea discharge of at least one of air, gas, and the viscoelastic substancefrom the contact module.
 11. The patient interface of claim 10, the oneor more output openings comprising: a vent port, configured to keep apressure in an accommodation space at least partially defined by thecontact module at approximately ambient pressure.
 12. The patientinterface of claim 1, comprising: a suction subsystem, configured to atleast partially immobilize the procedure eye for an ophthalmicprocedure.
 13. The patient interface system of claim 12, wherein: thesuction subsystem is arranged in relation to the contact module; and thesuction subsystem is connectable to a vacuum suction system to create apartial vacuum between the suction subsystem and the procedure eye. 14.The patient interface of claim 1, wherein: the patient interface isconfigured to keep a change of an apical curvature of a cornea of theprocedure eye below 10% upon an attachment of the patient interface tothe procedure eye.
 15. The patient interface of claim 14, wherein: thepatient interface is configured to keep a change of the apical curvatureof the cornea of the procedure eye below 3% upon the attachment of thepatient interface to the procedure eye.
 16. The patient interface ofclaim 1, wherein: the ophthalmic system includes at least one of animaging system, a diagnostic system, a laser system, or an ophthalmicsurgical system.
 17. The patient interface of claim 1, wherein: thecontact module is configured to accommodate the viscoelastic substancebefore being attached to the procedure eye.
 18. The patient interface ofclaim 1, wherein: the contact module is configured to accommodate theviscoelastic substance after the viscoelastic substance has been appliedto the procedure eye.
 19. The patient interface of claim 1, comprising:a soft film or membrane, configured to contain the viscoelasticsubstance in an accommodation space at least partially defined by thecontact module, and to form a soft contact surface for the procedureeye.
 20. The patient interface of claim 1, comprising: a soft bag,containing the viscoelastic substance.
 21. The patient interface ofclaim 1, wherein: the patient interface is connectable to a degassingsubsystem, configured to degas the viscoelastic substance.
 22. A patientinterface for an ophthalmic system, comprising: a contact module,configured to be attachable to a first eye with an apical corneal radiusof R1 and separately to a second eye with an apical corneal radius ofR2; and to limit a change of each apical corneal radius to less than0.5*|R1-R2| when the contact module is attached to the first eye andseparately to the second eye, wherein the apical corneal radii R1 and R2are between 7.5 mm and 8.2 mm.
 23. The patient interface of claim 22,wherein: the contact module is configured to limit the change of eachapical corneal radius to less than 0.25*|R1-R2| when the contact moduleis attached to the eyes.
 24. The patient interface of claim 22,comprising: an attachment module, attachable to a distal end of theophthalmic system, wherein the attachment module and the contact moduleare one of separate and connectable, or integrated components of thepatient interface.
 25. The patient interface of claim 22, comprising:one or more fluid ports, configured to introduce a fluid or gel into acontainment space at least partially defined by the procedure eye andthe patient interface.
 26. The patient interface of claim 22,comprising: one or more output ports, configured to enable a dischargeof at least one of air, fluid or gel from a containment space at leastpartially defined by the patient interface and the procedure eye. 27.The patient interface of claim 22, comprising: a suction port,configured to enable a creation of a partial vacuum between a portion ofthe patient interface and a portion of the procedure eye.
 28. Thepatient interface of claim 22, comprising: a distal lens, wherein thedistal lens does not contact a cornea of the procedure eye after anattachment of the patient interface to the procedure eye.
 29. Thepatient interface of claim 22, comprising: a soft layer, configured tocontain a viscoelastic substance, and to provide a soft contact surfacefor a procedure eye.
 30. A method of utilizing a patient interface foran ophthalmic procedure, the method comprising: applying the patientinterface to a procedure eye in preparation for the ophthalmicprocedure; and providing a viscoelastic substance to at least one of acornea of the procedure eye and a contact portion of the patientinterface, wherein the providing is performed before, during or afterthe applying.
 31. The method of claim 30, wherein providing theviscoelastic substance comprises providing at least one of: a fluid, aliquid, a gel, a cream, an artificial tear, a film, an elastic material,or a viscous material.
 32. The method of claim 30, the providingcomprising: introducing the viscoelastic substance through an input portof the patient interface into a contact space at least partiallybordered by the patient interface and the procedure eye after theapplying.
 33. The method of claim 30, the providing comprising:introducing the viscoelastic substance onto the cornea of the procedureeye before the applying.
 34. The method of claim 30, the providingcomprising: providing the viscoelastic substance at the contact portionof the patient interface before the applying.
 35. The method of claim34, the providing comprising: providing the viscoelastic substance in aspace at least partially defined by one or more soft films or membranes.36. The method of claim 30, the providing comprising: using a syringe tointroduce the viscoelastic substance.
 37. The method of claim 30,wherein the ophthalmic procedure comprises at least one of: an imagingprocedure, a diagnostic procedure, a laser-assisted procedure, or anophthalmic surgical procedure.
 38. The method of claim 30, comprising:degassing the viscoelastic substance.
 39. The method of claim 38, thedegassing comprising at least one of: reducing a pressure, heating,performing membrane degasification, substituting an inert gas, or addinga reductant.